The overall objective of this project is to understand the structure and function of the E. coli polA gene and of its gene product, DNA polymerase I. Our approach was first to determine the DNA sequence of the polA gene and then to use this information as a basis for the following investigations: 1) DNA sequencing of previously described polA point mutants so as to identify the mutational lesion and thus relate altered protein sequence (and structure) to defective enzymatic function. 2) Construction of additional polA mutants by in vitro or in vivo techniques, as dictated by the results of 1). 3) Identification of the DNA sequences controlling transcription of the polA gene.